This invention relates generally to an airflow deflecting assembly, and more specifically, is directed to an outdoor grill for an air conditioning unit having cambered grill elements oriented to control recirculation while reducing air-side losses and while reducing the noise produced by operation of an axial fan.
Air conditioning units, including heat pump units, which are commonly used for light commercial applications such as hotels, dormitories, and office buildings are often of the type known as a packaged terminal air conditioner (PTAC). These packaged terminal air conditioners extend through the wall of the enclosure and normally have an evaporator section in communication with the enclosure air for conditioning said air as it is drawn through the unit. A condensing section or outdoor section is located in communication with the outdoor ambient air for discharging heat energy during the cooling cycle. As with most air conditioning units a portion of the unit, having an indoor coil, is located within the enclosure to be conditioned while another portion of the unit, having an outdoor coil, is located in communication with the outdoor air. A grill structure is normally installed over each portion to prevent the entry of foreign objects while allowing the free flow of air to and from the portions. The axial fan on the outdoor side of the PTAC or other similar unit normally has a flat louvered grill as shown in U.S. Pat. No. Des. 267,338 and U.S. Pat. No. Des. 267,339 or a wire ring grill as shown in U.S. Pat. 4,818,183. If the louvers are parallel to the exhaust air stream, then control of recirculation from the discharge to the inlet is completely lost.
Moreover, if the louvers are pitched at a straight angle to the exhaust air stream, then turning losses and form drag losses are increased. Thus, although a straight angled grill reduces recirculation, the turning losses and form drag losses increase the pressure losses and hence, noise increases and fan power increases.